1. Field of the Invention
This invention relates to a method for fabricating a semiconductor device, and more particularly to a method most suitable for fabricating a diode, a transistor, an FET and integrated circuits, of the selective diffusion type in which a mask for impurity diffusion is used also as a passivation layer.
2. Description of the Prior Art
Hitherto, a SiO.sub.2 layer is used as a mask for impurity diffusion in the fabrication of a semiconductor device of the above-described type. The SiO.sub.2 layer remains on the semiconductor substrate, as a passivation layer. See, for example, U.S. Pat. No. 3,971,061 and U.S. Pat. No. 3,064,167. However, from the view-point of the characteristics of the semiconductor device, the SiO.sub.2 layer is so unstable against moisture that the leakage current changes under high humidity and that the reliability is deteriorated. Moreover, the semiconductor device using the SiO.sub.2 layer as the passivation layer has the disadvantage that it is deteriorated with the variations of electrical bias and temperature.